Determination of the presence of ex vivo products of conception in uterine tissue removed in therapeutic or spontaneous abortion is critically important to confirm the existence of uterine pregnancy and the termination thereof, and to rule out the presence of an ectopic pregnancy. If levels of fetal associated antigens in maternal serum or urine indicate pregnancy, and the uterine tissue removed during a therapeutic abortion contain no products of conception, a possible ectopic pregnancy is indicated. Presence of products of conception in uterine discharge associated with indicators of spontaneous abortion confirms the abortion, while the absence thereof indicated a continuation of pregnancy.
Usual immunoassay methods for determining the presence of fetal associated antigens in uterine tissue samples are not reliable for indicating the presence of products of conception since these samples typically contain maternal blood. Nonrestricted fetal antigens are usually present in maternal blood as well as in fetal and placental tissue.